This invention relates to wrapping loads on pallets, more particularly the wrapping of a load such as a stack of filled bags or boxes on a pallet.
Wrapping such pallet loads to stabilize them on the pallet, i.e., to maintain them intact on the pallet, has become widespread practice. Heretofore, various modes of wrapping have been employed for this purpose. One such mode (referred to as stretch wrapping) involves the wrapping of stretchable plastic film around the load, and stretching of the film as disclosed in U.S. Pat. No. 3,867,806, for example. Another mode (referred to as shrink wrapping) involves the wrapping of heat-shrinkable plastic film around the load or the placement of a cover (a bag) of such film as a wrapping over the load, and heating the wrapping as by conveying the pallet with the enwrapped load thereof through an oven (which may be referred to as a shrink tunnel) for heating the wrapping to cause it to shrink on the load. Each of these modes has the distinct disadvantage insofar as many loads are concerned that air cannot circulate through the wrapping. Thus, for example, a load of bags of flour, which bags are palletized in a warm condition, generally cannot be stretch wrapped or shrink wrapped because of condensation of moisture within the wrapping when the bags cool, causing damage to the product. Further by way of example, a load of fresh produce in ventilated packages, the produce requiring ventilation, cannot be stretch or shrink wrapped. A mode of wrapping products utilizing a sleeve of heat-shrinkable plastic netting so as to provide ventilation has been proposed - see U.S. Pat. No. 3,945,493--but this requires heat-shrinking of the sleeve by passing the pallet with the ensleeved load thereon through an oven, and this may damage certain products (e.g., fresh produce) or be dangerous in the case of certain products (e.g., presenting a fire hazard), as in the case of flour. A fourth mode had involved banding the load with steel or plastic strapping. Conventional steel and plastic strapping has very little elasticity and consequently when applied to a pallet load tends to loosen and cease holding the load securely as the load, in the case of flowable product in bags, compacts or, in the case of wet produce in corrugated cardboard cartons, the carton walls weaken and collapse. While both the heat-shrunk netting and strapping provide for air circulation, they do not hold many pallet loads securely through the numerous handlings the pallet may receive.